Orkoula Malvina G, Koutsoukos Petros G
Department of Chemical Engineering, University of Patras, Patras, Greece.
J Colloid Interface Sci. 2002 Sep 1;253(1):185-9. doi: 10.1006/jcis.2002.8536.
Dissolution processes play an important role in marble weathering. Investigation of the dissolution kinetics of powdered Pentelic marble, a calcitic natural stone, showed that the rates measured at constant undersaturation decreased with time. It was found that the rate of dissolution decreased sharply to about 50% of the initial value before 5% of the initially suspended powder was dissolved. Past a dissolution extent corresponding to 25% with respect to the suspended solid, the rates of dissolution at the same constant undersaturation reached a stable value corresponding to 20-25% of the initial rate measured. The reduction in the rates of dissolution up to 25% of mass loss was in agreement with the reduction in the total surface area exposed to the solution, suggesting a dependence of the rate on the number of active sites on the surface of the dissolving material. The decrease in the dissolution rates did not depend on the undersaturation of the solution or on the physical characteristics of the particles such as specific surface area, porosity, and particle size distribution. Equal mass losses, with respect to the initially suspended solid, of different samples exhibited the same relative decrease in rate regardless of the conditions of the aqueous solutions.
溶解过程在大理石风化中起着重要作用。对一种钙质天然石材——彭泰利克大理石粉末的溶解动力学研究表明，在恒定不饱和状态下测得的溶解速率随时间下降。结果发现，在最初悬浮粉末溶解不到5%之前，溶解速率急剧下降至初始值的约50%。超过相对于悬浮固体25%的溶解程度后，在相同恒定不饱和状态下的溶解速率达到一个稳定值，相当于所测初始速率的20 - 25%。溶解速率降低至质量损失25%之前，这与暴露于溶液中的总表面积减少相一致，表明速率取决于溶解材料表面活性位点的数量。溶解速率的降低并不取决于溶液的不饱和程度，也不取决于颗粒的物理特性，如比表面积、孔隙率和粒度分布。不同样品相对于最初悬浮固体的等质量损失，无论水溶液条件如何，其速率都表现出相同的相对下降。
